The present invention relates to a profile for sliding windows or doors, the method for obtaining this profile and the window or door which can be obtained with this profile.
The sliding windows or doors usually consist of:                a fixed frame (the most simple and usual versions also having a fixed sash positioned on a first track);        at least one movable frame or sash which slides horizontally opening and closing relative to the fixed frame (parallel with the fixed sash);        a pair of carriages, associated on the lower crosspiece of the movable sash and resting on a second horizontal track (parallel with the first track on which the fixed sash rests), and designed to allow the movable sash to slide in both directions;        a control element positioned on the sash and designed to control operating means with which it is possible, respectively, to release the sash relative to the fixed frame and allow it to slide so that it opens, and to lock the sash in a closed position, in which it is stably associated with the fixed frame;        closing means acting at least between the vertical stile of the sash and the vertical stile of the fixed frame (opposite one another and in contact in the closed configuration).        
The sliding window or door structured in this way is amongst the most widespread and most used on the market, since it has a high level of active safety and is suitable for architectural solutions which require large glass window or door surfaces combined with limited overall dimensions.
However, in contrast to these undoubted advantages of the sliding window or door there is an insufficient level of heat insulation relative to the other types of windows or doors (see for example windows and doors with tilt and turn opening).
The causes of this insufficient heat seal may mostly be attributed (partly based on the many tests carried out) to the fixed frame of the window or door.
More precisely, the lower rail A and upper rail of the fixed frame, rails consisting of a base profile PB from which the two tracks B1 and B2 emerge, having common surfaces between the inner zone ZI and the outer zone ZE of the environment in which the window or door is mounted: said common zones are identifiable, in particular, in the above-mentioned parallel pair of sliding tracks B1 and B2.
The architecture used to allow the sliding of the sash or sashes A1 and A2, with relative overlapping of the sashes, leaves uncovered a good part of the surfaces corresponding to the sliding tracks B1 and B2, in the sense that there is a passage of heat between the outside and the inside (see FIGS. 1 and 2).
To overcome this deficiency there are currently solutions defined as being of the “thermal break” type, which can be produced on extruded aluminum profiles and substantially consist of bars G of polyamide (a material with a low level of heat transmission) which separates—in the middle—along the whole length the profile of each crosspiece of the window or door.
Thermal energy, that is to say heat, flows from one environment to another in three basic ways: conduction, convection, irradiation. The direction of transmission is from the environment with the higher temperature towards the environment with the lower temperature. If the two environments are separated by a partition, the amount of heat which passes through it is proportional to the difference in temperature.
In the case of the sliding windows or doors (as clearly shown in FIGS. 1 and 2), this thermal break system on the frame does not allow acceptable performance to be achieved because the metal surfaces of the rails with faces common to the outside and inside, are never completely separate and so still allow the passage of heat by conduction from the inside to the outside and vice versa on the individual tracks even in the presence of the insulating bars forming the thermal break and the presence of seals on the two sides of the profile of the movable frames or sashes present which, in the closed position, are in contact with the tracks.
Another particularly critical element of the sliding window or door as regards the heat seal is identifiable in the central zone in which the sashes A1 and A2 overlap in the closed configuration (the sashes obviously being fitted with seals on the vertical elements in the widely known way).
As FIG. 1 clearly shows, the space between the two tracks, common to the inside and the outside, may lack a heat seal: at present this zone is protected with an element G which—in theory—acts as a “seal”, even if it has very approximate performance and absolutely does not allow a thermal break along the profile.
In addition to this the new energy saving regulations will make it difficult to use this type of window or door if its performance cannot be adjusted in terms of insulation.